gchristopher

I'd like to again nominate an (unintentionally) connected series of challenge threads for Heritage status. The basic idea for each is: figure out how to reload and reuse a launch vehicle for multiple payloads without bringing it back into the VAB/SPH. Each one necessarily puts the focus on the same hardest part: building the support machinery to accomplish the ground operations. The three very similar threads (that I know about) are: And the recently started by @Kerbolitto: The particulars of each are different, but each one requires a very similar set of problems to solve to complete. For the two (edit) three most recent, the poster didn't know there was an interesting history of this challenge being done in the past. It seems like a shame that this fun idea (if in slightly different incarnations), isn't recorded as a Heritage Challenge series. Since the threads have different titles and slightly different approaches to reaching the same basic challenge, I'm not sure what you'd name it, but this idea deserves to be recorded here somehow. Edit: Also, here's a fourth challenge that had basically the same "refuel and reload your lifter outside the VAB/SPH" as "Harder Mode":

Those are good ideas! I've been thinking about it, but I think the time commitment and current game bugs/glitches will probably stop me this time around. I was working on the basic pieces you'd need for a challenge like this. Stock robotic parts are REALLY shaky and unstable right now, wow. Eventually I figured out that if you use pistons as adjustable springs (pull force only), and ensure that there's never any lateral forces, they seem stable. But that was after discarding a dozen attempts at gantries and pushback trucks. Mostly when I connect two ground vehicles, one or both instantly explode. Here's the lifter and gantry I got working. The spaceplane is just under 300 tons and can carry just over 200 tons to LKO, for a 40.8% payload fraction, which won't win any efficiency contests, but is pretty respectable for being flexible enough to drag anything with a fairing into orbit. I was able to get a pushback truck to work, using a single piston to adjust the docking port height, with VERY careful force vector management and manual struts. Where I gave up was when I made a simple fuel truck, put as many of the giant wheels on it as would fit, launched it, and watched it skitter sideways across the runway, even without any robotic parts. Given how many hours it takes to do a challenge like this, I think I have to wait for the game to recover some stability from the last few rounds of updates. I think you could include spaceplanes in this challenge just fine, btw. To me, this challenge should count as the third iteration of a Heritage challenge series, where the basic idea is "build ground operations to support repeatedly flying missions using a single lifter without using the VAB/SPH." The first challenge was: An Affordable Space Program: making the reusable spacecraft pay off. The second was: [REUSEABLE ROCKET] 1 Rocket 1 Station I think the only thing this challenge is missing to be a full continuation of the series is some goal, to put a station into orbit in pieces, or to fly service missions to en existing station, or shuttle resupply fuel to orbit, or something. Basically, do all the cool ground stuff, AND prove that it all works by flying a few missions that put it all to use. I'll keep poking at my heavy lift spaceplane. If I can just get wheels to start sticking to the ground, then the only real technical barrier is that a moderately optimized SSTO spaceplane tends to need a long runway. I played around a bit with docking booster carts to the underside and was able to achieve a pretty short-distance take-off, but again, that's a lot of ground-wheel interaction, which just seems extremely buggy in 1.7.3.

I've been wondering how to adapt this challenge to making an airfield for a reusable spaceplane? It'd be fun and not too crazy to assemble an equatorial desert airstrip by driving the parts north from the built-in desert launch site. In the spirit of the list you've made above, I think you'd probably also need additional things like: An air control tower One or more weather stations for wind forecasting. (Maybe a weather radar?) Pushback tractor Runway beacons/lights (probably critical for practical Mobile crew ladder Fire/emergency service vehicles and fire station If not a full hangar, then some kind of designated aircraft service area for loading a new payload Crew and snack supply vehicles. (For transport to/from support facilities or a designated "civilian/commercial transport hub") The actual infrastructure to bring a payload to the airstrip and mount it to the spaceplane. (Using clamp-o-trons and autostruts for stability) What's missing there?

This challenge has a lot like the classic Affordable Space Program Challenge: That challenge (before funds and recovery were added) was to assemble a space station from at least four launches, reusing the same launch vehicle for all launches. This required building refueling vehicles, payload gantries, or entire launch gantries. (if launching vertically and landing horizontally) My entry for that one included ridiculous pre-aero concepts like a vertically launched SSTO rocket that was unable to land safely or accurately at KSC, so a spaceplane rendezvoused with it in orbit. That spaceplane (the "Hot Dog Bun") split down the middle and attached to either side of the rocket, and the entire 3-part assembly landed on the runway. Separate the entire mess, tow the rocket away to get a new payload, push the two halves of the spaceplane back together, fuel them all back up, regret your life choices, and repeat! Highly Technical Mission Profile by Bill: https://imgur.com/a/6nqre It's cool to see this now that the mechanical pieces are now stock!

There was a more recent 1.3.x reboot of that challenge here: @ATEC announced in a previous Heritage thread that the challenge is open for reboot.

If the entrant shows the funds recovered after returning to KSC, that should be deducted from the cost of the launch. That's the whole point of building a reusable vehicle in KSP. Separate leaderboards is a good way to go with that, but to keep it consistent with the game and many past challenges of this kind, you're best off reporting the cost based on the actual money spent and recovered in game. i.e. Cost = [Cost at Launch] - [Cost of Payload] - [Amount Recovered] Otherwise your readers (like me), are very confused as to how a non-reusable entry did so much better than the reusable ones, and have to sift through your discussion before realizing, "oh, this guy ignored funds recovered. That doesn't match how KSP works." Obviously entrants should show the actual funds recovered screen, because you spend fuel getting back down, and accurately landing matters for the recovery percent, too. You've got separate leaderboards so you're not marginalizing the efforts of the non-recoverable people, but by ignoring the recovery amounts, you're misleading readers about the actual performance they'd get from the different crafts if they used them in their own games.

Nice!! Way to go!

^^ This. Once you've flown 100 or more flights where you have to carefully simulate just the right analog input by tapping an arrow key at JUST the right frequency, it's time to recognize that being good at that skill is a silly life goal. Buying a good flight joystick is an option, but using an autopilot to hold the controls at exactly 43% up is fine too. Autopilots should be permitted for this challenge. All the people who achieved good payload fractions used understanding of design and aerodynamics, and the flight portion came down to figuring out the right flight profile and engineering a craft that could fly it. Skillfully timed key-mashing shouldn't be part of the contest just because they don't own a joystick.

Nice! The "Harder Mode" rules for this challenge are about the same as the old Affordable Space Program challenge. You'll find a lot of entries (pre-1.0 aero) there, too. KAS is great for this, as well as Infernal Robotics for ground operations.

@sevenperforce Thank you very much for explaining that! That's very cool.

Nice entry! Is that attachment trick explained anywhere? I'm endlessly frustrated by spaceplanes because it seems like the only way to discover drag is to launch something, watch the numbers in the physics debug screen change inscrutably, try to guess a reason, change something and start over. Any part stats related to drag seem to be completely hidden.

That's pretty cool!

So, the basic idea is to clip some small parts inside a larger part, then decouple them and that makes a bearing? (Without just installing IR.)

KAS or other placeable struts are still required to dock two objects securely enough to avoid ridiculous wobble. KJR helps, but isn't enough. The game still needs something like a "locking" docking port that, once connected, is at least as strong as an in-line or radial separator. Clamping/locking mechanisms are not exotic technology and docking ports aren't remotely up to the task of loading a heavy payload into a large docking bay, for example. I'm aware this has been suggested many times. Posting a new topic to avoid a necro that might have debate about much older versions. It's still a pretty big missing piece of the game, especially for doing very large assembly in orbit, or when intentionally limiting cargo size to force interesting orbital operations.

Thanks! I tried it, and it's only partially successful. Some UI elements scale correctly, others, like the total science/funds display, vanish entirely in key places, like the research center. (Try picking what to research when you don't know how much science you have!) I think for now, in 1.3, KSP simply isn't playable in 4K without some fixes by the developers for the UI.

On a 4K monitor, 150% is not enough to bring most of the UI back to a usable size, especially control buttons like take crew reports, etc. Can the max UI scale be increased? That'd help a lot to lower eyestrain and make the UI easier to navigate. (Obviously reducing the resolution is an option, but since even last year's graphics card keeps up with the game easily, it'd be sad to lose the nice native screen resolution.)

Huh? That's not abuse. It's shielded on reentry by the rest of the craft. No exploits at all and only stock parts. "Smallest" or "minimum" challenges tend to have the problem of fewer entries because once someone hits on the minimal part combination, there isn't room for improvement, and KSP generally has one best answer to questions like that. I doubt that what I did is minimal, though, especially the ascent stage.

Normal Mode: At launch: 253 Oxidizer, 279 Liquid Fuel. Landed at Mun: At landing on Kerbin: 4.06 Oxidizer, 3.32 Liquid Fuel Total Fuel used: 248.94 Oxidizer, 275.68 Liquid Fuel, Total Used: 524.62. It is possible to get that well under 500 with a pilot that cares. No autopilot was used, but given that it's stupid keyboard input, that's more an act of masochism than an achievement to be proud of. Craft File

Uh-oh @Nefrums! That's 29 hundredths of a percent less than your 1.0.5 record! edit: Oh wait. This challenge is 100x100 instead of 70x70 for the old challenge. So this run is actually significantly better. I think the spaceplane percents in the OP are off still. There's still the extra 10 added to the payload fraction reported as the percentage.

This challenge is a little taste of the things people did in the Affordable Space Program challenge by @SirJoab. (Which is still my favorite challenge by far.) That covered a broad range of KSC-grounds surface vehicle jobs for refueling and reloading mission payloads. For a more flexy/stretchy articulated joint, you can use some docking port jr's in series. Here's a two-tanker fuel truck that did that. In this case, the fueling arm used Infernal Robotics. A claw set to rotate will pivot freely like a ball hitch. This can be used to make sturdy multi-trailer fuel trucks, for example. It's also worth considering KAS for connections. If I were to do the whole challenge, I'd definitely use TweakScale for even bigger monster truck wheels!

I was able to fly a rip-off of Nefrum's Stingray Mk14 (rebuilt to be visually similar) to a 75x75 orbit and return, leaving a 48% payload fraction in orbit. That's not my design, so not really fair to enter here. Plus, no autopilot assist is a non-starter for KSP-playing these days. I put in enough hundreds of missions doing the "carefully tap a key to get just the right analog control" routine (wow, in 2014) that flying without an autopilot isn't worth the frustration. That's a level of masochism that's happily left in the past. I sympathize with those who haven't hit that breaking point. I held out against using Mechjeb for an awfully long time, too. That test flight was quite a bit lower than the 58% that Nefrum posted in 1.0.5. I can't really tell how much of that is due to aero changes, engine changes, or my own semi-ignorant understanding of the ascent profile. Still, me getting 48% to 75x75 that seems to indicate that someone actually competent can probably get 50% to 100x100! That's encouraging, because it hopefully puts 25%-30% into the range of payload fractions for routine, not-pushing-the-envelope flights. Thank again or reviving this, @ATEC! I hope people keep posting and filling out the thread with attempts!

It's good to see this restarted. The Stock Payload Fraction Challenge was always where I looked to see how well KSP was doing as a game. More than any other challenge (except maybe the corresponding funds/ton challenge), this one had the best players taking on the most difficult part of the game to optimize. When this challenge went inactive, it was kind of a death-knell for KSP challenges in general, and corresponded to a much lower level of activity, interest, and creativity in the game and the forums. Has the game changed so dramatically that the prior best (>50% payload fraction in 1.0.5) has been reduced to 35% as the best now? It'll be neat to see others try! I never understood how you are able to measure drag; how does everyone figure out that critical value?? (Also, thanks for the craft file @Wanderfound! I haven't played in quite a while, and after cutting the payload in half and semi-incompetently following the ascent profle, I was able to launch, reach orbit, and land the spaceplane on the runway without autopilot on the first try! That's a pretty forgiving design, especially with me significantly miss-guessing reentry and overshooting the runway by a lot.) edit: Oh, a couple requests for @ATEC: please consider linking to the relevant post in the leaderboard. As the thread grows, that'll make them easier to browse to. Also, drop the 10 point recovery bonus for spaceplanes. All that does is obfuscate the payload fraction when every other category is clearly scored by payload percent. Make a separate category for recovery if you want to track recovery, or just require that all spaceplanes return to Kerbin.

The Affordable Space Program challenge was a featured thread and attracted a wide variety of complex and varied entries. It uniquely required development of ground operations and more complicated docking operations. Since it required multiple launches and landings with the same craft, there was a higher level of effort, so it's not one with hundreds of entries, but what entries were completed were extremely high quality. This challenge made you actually use a reusable craft (SSTO) for what it was meant to do, and if your landing wasn't accurate, you paid more than just a few funds to return the craft; you actually dealt with getting it back to KSC for refueling and mounting a new payload.

Under the pre 1.0 aero, did something a little more complicated than this with the Sporklift/Hot Dog Bun launch system, where a rocket lifted the main payload, then a spaceplane launched, split right down the middle, then welded itself to either side of the rocket to deorbit. This was for the Affordable Space Program: making the reusable spacecraft pay off challenge, which remains the favorite challenge of any I've ever seen posted here. Oh, imgur albums don't work anymore! Album here. That's annoying. The main problem is that docking ports don't lock and are absurdly weak for purposes like this one, then and now. You pretty much have to use multiple docking ports, or find a strut or reinforcement mod. Obviously old-aero design won't work now, but the approach might.